The present invention relates generally to apparatus for metering and controlling fluid flow and more particularly to a device to provide an immediate and continuous measurement and control of a flowing fluid whereby a desired flow rate of the fluid may be established. The invention is especially applicable in devices for controlling the flow of fuel in internal combustion engines and the invention will be particularly appropriate for use on motor vehicles.
Apparatus of the type to which the present invention relates is disclosed in U.S. Pat. No. 3,633,420. The apparatus disclosed in this patent has been used particularly in connection with testing apparatus, for example in motor vehicle workshops where simple and quick determination of fuel consumption is desired. Such apparatus may be mounted in a vehicle during a test run or it may be used in a laboratory where tests are performed.
It will be apparent that apparatus of this type is particularly useful in view of the present day concern with energy conservation. Clearly, the consumer has undergone a significant increase in the awareness of the significance of energy sources and this awareness has led to a desire to provide for economically enhanced utilization of available fuel supplies. Of particular significance is the consumption of fuel in motor vehicles and great efforts have been directed toward this goal. Particularly, owners of motor vehicles are now giving consideration to matters of fuel consumption when purchasing a vehicle and during its operation. Furthermore, manufacturers of automobiles make available data regarding fuel consumption of the vehicles in response to public demand for such data. Despite the fact that data of this type are published, the statistics involved tend to be only approximate and lacking in optimum accuracy. Furthermore, most vehicles are not equipped to provide a continuous indication of the fuel consumption economy of the vehicle during its operation nor are there provided instruments to enable continuous indication of the fuel consumption characteristics of the vehicle in order to enable optimum adjustment of driving behaviour.
Thus, it will be found that while the prior art devices will make possible satisfactory measurements or indications for test purposes, such arrangements tend to be extremely cumbersome if installed as standard equipment on motor vehicles and because of this they have been found to be unacceptable for this purpose.
The present invention is based upon the goal of providing an apparatus of the type discussed which is simpler in structure and operation to such a degree that it may be found suitable for permanent installation particularly as standard equipment in motor vehicles with the equipment being provided at reasonable costs.
In evaluating the specific objects sought to be achieved by the equipment and design of this type of apparatus, it will be found that three essential components must be provided. First, apparatus of this type will generally include a positive displacement type of measuring device through which the flow is passed and by which the flow rate is measured. Secondly, a pressure sensing means is provided to sense the pressure developed between the inlet and outlet of the flow meter. Thirdly, the equipment will include a servo drive mechanism which, in known devices, is usually an electronically controlled electro motor.